The present invention relates to an image read/write head having both an image-reading function and an image-forming function, and to an image processing apparatus incorporating the same.
Image processing apparatuses, such as a facsimile apparatus, need to have both an image-reading function and an image-forming function. Further, there exists a demand to be met for the downsizing of such image processing apparatuses. Accordingly, image read/write heads have been proposed which are capable of reading images as well as forming images. One such image read/write head is of the construction shown in FIG. 19. Image read/write head H shown includes a case 1e having an upper portion defining an opening fitted with a transparent cover 19e. In the case 1e is disposed a light source 3e for illuminating a reading line Se established on the transparent cover 19e. The case 1e is further fitted at the bottom thereof with an elongate substrate 4e having upper and lower surfaces 40 and 41 carrying a row of light-receiving elements 2e and a row of heat-generating elements 8e, respectively, longitudinally of the substrate 4e. 
With the image read/write head H thus constructed, a document D to be read is fed while intimately contacting the transparent cover 19e by rotation of a platen roller P1 for feeding documents. In this process the document D is illuminated by light from the light source 3e. The light reflected by the document D is gathered by a lens 5e disposed between the reading line 5e and the light-receiving elements 2e, so that the image of the document D is formed on the row of the light-receiving elements 2e. In this way, the image data of the document D is obtained. On the other hand, recording paper K is fed while intimately contacting the heat-generating elements 8e by rotation of a platen roller P2 for feeding recording paper. In this process the image of the document D is formed on the recording paper K by causing appropriate ones of the heat-generating elements 8e, which are selected according to the image data of the document, to generate heat.
As described above, the image read/write head H is constructed such that the document D is fed while intimately contacting the transparent cover 19e fitted in the opening defined in the upper portion of the case 1e, whereas the recording paper K is fed while intimately contacting the heat-generating elements 8e mounted on the lower surface 41 of the substrate 4e. Stated otherwise, the platen roller P1 for feeding documents is positioned above the image read/write head H, while, on the other hand, the platen roller P2 for feeding recording paper is positioned below the image read/write head H. Such positioning of the platen rollers P1 and P2 makes it difficult to reduce the vertical dimension of an image processing apparatus incorporating the image read/write head H, hence, to downsize the whole apparatus.
It is, therefore, a main object of the present invention to provide an image read/write head which, when incorporated in an image processing apparatus, allows such an image processing apparatus to be remarkably downsized.
According to a first aspect of the present invention, there is provided an image read/write head comprising:
a substrate having a first widthwise side portion, a second widthwise side portion, and an upper surface carrying a row of light-receiving elements longitudinally of the substrate;
an elongate case mounted to the upper surface of the substrate to enclose the light-receiving elements;
a transparent cover mounted to an upper surface of the case for contact with a document to be fed;
a light source disposed in the case for illuminating the document;
a lens unit disposed in the case for causing an image of the document illuminated by the light source to be formed on the light-receiving elements; and
a row of printing elements carried by the upper surface of the substrate at an excess portion which is provided by extending the first side portion beyond a lower edge of the case by a predetermined amount;
wherein the transparent cover is inclined such that the cover becomes progressively farther from the substrate as it extends toward the first side portion of the substrate.
In the above construction, the printing elements are, typically, heat-generating elements for recording an image on recording paper by thermal transfer printing or thermal recording. In constructing an image processing apparatus incorporating the image read/write head of the above construction, the platen roller for feeding the document for contact with the front surface of the transparent cover and the other platen roller for feeding the recording paper for contact with the printing elements are both positioned on the same side of the substrate, whereby the image processing apparatus can have a remarkably reduced thicknesswise dimension.
Further, since the transparent cover of the image read/write head is inclined in the manner described above, the platen roller for feeding the document and the platen roller for feeding the recording paper can be disposed with a positional relationship such as to have a reduced distance therebetween in a plane perpendicular to the major plane of the substrate with an adequate distance being secured between the two rollers in the major plane of the substrate. This arrangement enables further downsizing of the image processing apparatus in the thicknesswise dimension while allowing the respective feeding paths of the document and the recording paper to be set appropriately without any interference therebetween.
According to a second aspect of the present invention, there is provided an image read/write head comprising:
a substrate having a first widthwise side portion, a second widthwise side portion, and an upper surface carrying a row of light-receiving elements longitudinally of the substrate;
an elongate case mounted to the upper surface of the substrate to enclose the light-receiving elements;
a transparent cover mounted to an upper surface of the case for contact with a document to be fed;
a light source disposed in the case for illuminating the document;
a lens unit disposed in the case for causing an image of the document illuminated by the light source to be formed on the light-receiving elements; and
a row of printing elements carried by the upper surface of the substrate at an excess portion which is provided by extending the first side portion beyond a lower edge of the case by a predetermined amount;
wherein the lens unit is inclined toward the second side portion.
Like the image read/write head according to the first aspect of the present invention, this image read/write head has the platen roller for feeding the document and the other platen roller for feeding the recording paper, both positioned on the same side of the substrate, whereby an image processing apparatus incorporating this image read/write head can have a reduced thicknesswise dimension.
Further, this image read/write head has the lens unit inclined toward the second side portion of the substrate. Since the lens unit is adapted to cause an image at an image-reading line defined on the transparent cover to be formed on the row of light-receiving elements, the above construction is meant to have the reading line on the transparent cover displaced relative to the light-receiving elements on the substrate toward the second side portion of the substrate. Since the platen roller for feeding the document is positioned to come into contact with the reading line, this construction also can secure an adequate distance between the platen roller for feeding the document and the platen roller for feeding the recording paper, thereby allowing the respective feeding paths of the document and the recording paper to be set appropriately without any interference therebetween. Further, this construction can secure a sufficient optical path length between the reading line and the light-receiving elements thereby increasing the focal depth of the lens. This leads to an improvement in the quality of an image thus read.
According to a third aspect of the present invention, there is provided an image read/write head comprising:
a substrate having a first widthwise side portion, a second widthwise side portion, and an upper surface carrying a row of light-receiving elements longitudinally of the substrate;
an elongate case mounted to the upper surface of the substrate to enclose the light-receiving elements;
a transparent cover mounted to an upper surface of the case for contact with a document to be fed;
a light source disposed in the case for illuminating the document;
a lens unit disposed in the case for causing an image of the document illuminated by the light source to be formed on the light-receiving elements; and
a row of printing elements carried by the substrate at an excess portion which is provided by extending the first side portion beyond a lower edge of the case by a predetermined amount;
wherein the case has a lateral surface on a side closer to the first side portion of the substrate, the lateral surface being inclined toward the second side portion of the substrate.
Like the image read/write head according to the first aspect of the present invention, this image read/write head has the platen roller for feeding the document and the other platen roller for feeding the recording paper, both positioned on the same side of the substrate, whereby an image processing apparatus incorporating this image read/write head can have a reduced thicknesswise dimension.
Further, this construction also can secure an adequate distance between the platen roller for feeding the document and the platen roller for feeding the recording paper, thereby allowing the respective feeding paths of the document and the recording paper to be set appropriately without any interference therebetween.
In a preferred embodiment of the image read/write head according to any one of the foregoing aspects of the invention, the case and the substrate are assembled together by engagement means for bringing the substrate or a member integral with the substrate into engagement with the case. Such an arrangement improves the operability of assemblage of the case and the substrate together.
In a further preferred embodiment, the engagement means is configured to cause longitudinally opposite ends of the case to engage the substrate or a member superposed on the substrate. Such an configuration allows the longitudinally opposite ends, in particular, of the case to be secured to the substrate while stabilizing the assembly with the number of parts of the engagement means reduced.
In a further preferred embodiment, the engagement means is configured to cause a portion of the case adjacent the printing elements transversely of the case to engage the substrate or the member superposed on the substrate. Such a configuration is capable of preventing the case and the substrate from defining a clearance therebetween at that portion of the case adjacent the printing elements, thereby avoiding the occurrence of a feeding failure such as catching of the recording paper by the clearance which would otherwise be defined between the case and the substrate.
In a further preferred embodiment, the case has a bottom surface facing the substrate, the bottom surface having a longitudinally central portion bulging relative to longitudinally opposite ends of the case when the case is in a natural state. Such a configuration is capable of appropriately preventing the central portion of the case from being raised relative to the substrate when the case is engaged at the opposite ends thereof with the substrate or a heat sink plate, thereby avoiding the occurrence of a feeding failure such as entry of the recording paper into the clearance which would otherwise be defined between the case and the substrate.
A preferred embodiment of the image read/write head according to the first or second aspect of the invention further comprises a single or plural guide means provided integrally with or separately from the case, the substrate or a member integral therewith for guiding feed of at least one of the document to be delivered to a front surface of the transparent cover and the recording paper to be delivered to a region of the substrate carrying the printing elements. Such an arrangement allows the document and the recording paper to be fed properly without any interference between the two, despite the fact that the document and the recording paper are to be fed relatively closely to each other on the same side of the substrate. Further, since the image read/write head is provided in itself with the guide means for guiding feed of the document or the recording paper, an image processing apparatus incorporating this image read/write head can have a simplified peripheral structure around the head and, hence, can be assembled easily.
In a further preferred embodiment, the case is provided with a first guide surface extending outwardly from one side edge of the front surface of the transparent cover, the first guide surface being defined by a ridge protruding toward the first side portion of the substrate, and a concave second guide surface rising thicknesswise of the case from a portion adjacent the printing element carrying region of the substrate, the first and second guide surfaces forming the guide means. With such an arrangement, the first guide surface is capable of properly guiding the document to the front surface of the transparent cover, while the second guide surface is capable of properly guiding the recording paper to the printing element carrying region of the substrate. Further, since the second guide surface is concave, the advancing direction of the recording paper guided by the second guide surface can be largely changed to the extent that it is substantially reversed, whereby the recording paper can be prevented from interfering with the document. Furthermore, the image processing apparatus can further be downsized by positioning part of the platen roller for feeding the recording paper proximately to and as embraced by the concave guide surface.
A preferred embodiment further comprises a heat sink plate superposed on a reverse side of the substrate, the heat sink plate having an extra portion extending beyond the first side portion of the substrate, the extra portion defining a third guide surface continuous with a portion of the substrate adjacent the printing element carrying region of the substrate. This arrangement allows the recording paper to be fed more properly by cooperation of the third guide surface defined by the heat sink plate and the second guide surface defined by the lateral surface of the case.
In a preferred embodiment of the image read/write head according to the second aspect of the invention, the light-receiving elements provide a row of light-receiving faces extending in a primary scanning direction, each of the light-receiving faces having a secondary scanning direction width which is larger than a pitch between the light-receiving faces in the primary scanning direction.
In the image read/write head according to the second aspect of the invention, the lens unit is inclined and, hence, the light-receiving face of each light-receiving element receives light having passed through the lens unit not perpendicularly but obliquely. Though the amount of light received by each light-receiving face per unit area decreases accordingly, the construction according to the second aspect intentionally expands the dimension of each light-receiving face in the secondary scanning direction to avoid a decrease in the total amount of light received by each light-receiving face, thereby avoiding a degradation in the quality of an image read.
In a preferred embodiment, the case has inner wall surfaces defining an internal space of the case, at least part of the inner wall surfaces serving as a reflective surface which is rendered white to provide a high light-reflectivity.
Light emitted from the light source travels in the internal space defined by the inner wall surfaces while being reflected by the inner wall surfaces. In the above construction, the inner wall surfaces have a high light-reflectivity. For this reason, this construction can reduce a loss of light emitted from the light source during traveling as compared with a conventional construction in which inner wall surfaces defining such an internal space is formed of a black-colored resin having a lower light-reflectivity. Stated otherwise, the above construction according to the present invention is capable of efficiently leading light emitted from the light source to the image reading region while allowing such light to be reflected by the reflective surface at a high reflectivity.
The image read/write head according to this embodiment, accordingly, is not required to use a light source emitting a large amount of light or a multiplicity of light sources for illuminating the image reading region with a higher illuminance. This allows the manufacturing cost of the image read/write head as well as the running cost to be reduced. Further, since this image read/write head meets an essential requirement such as to illuminate the image reading region with a high illuminance, it is possible to upgrade the quality of images read, hence, improve the reproducibility of the image of a document recorded on the recording paper.
It should be noted that the present invention may employ appropriate means for making the inner wall surfaces defining the internal space serve as the reflective surface which is rendered white, for example, means for forming the case entirely of a white-colored resin, means for applying a white-colored coating on the inner wall surfaces, or means for affixing a white-colored member such as a white-colored sheet to the inner wall surfaces defining the internal space.
Where the case is formed entirely of a white-colored resin, it is preferred that the case should have a chamber for accommodating the light-receiving elements, the chamber being provided with reflection-preventive means covering inner wall surfaces of the chamber to enclose the row of the light-receiving elements, the reflection-preventive means including a light-absorptive surface having a lower light-reflectivity than the inner wall surfaces of the chamber.
In such an arrangement, the chamber in which the light-receiving elements are to be disposed is provided with the reflection-preventive means thereby forming the light-absorptive surface having a low light-reflectivity around the row of the light-receiving elements. Thus, irregular reflection of light within the chamber can appropriately be prevented and, hence, such a situation can be avoided that most of irregularly reflected light becomes incident on the light-receiving elements. Accordingly, it is possible to avoid a decrease in the resolution of an image read or in the reproducibility of the image of a document, which would otherwise occur due to the case formed entirely of a white-colored resin.
The above light-absorptive surface is formed of a black-colored member fitted in the chamber. Alternatively, the light-absorptive surface may be formed of a black-colored coating applied on the inner wall surfaces of the chamber, or a black-colored sheet or film bonded to the inner wall surfaces of the chamber.
Other features and advantages of the present invention will become more apparent from the following detailed description given with reference to the attached drawings.